The Lahontan cutthroat trout was originally listed as endangered
in 1970 but was downlisted to threatened in 1975. A recovery plan
was published in 1995. There is no critical habitat designation.

Historical
Status and Current Trends

Lahontan cutthroat trout historically occurred in most cold waters
of the Lahontan Basin of Nevada and California, including the
Humboldt, Truckee, Carson, Walker, and Summit Lake/Quinn River
drainages. Large alkaline lakes, small mountain streams and lakes,
small tributary streams, and major rivers were inhabited, resulting
in the present highly variable subspecies. Only remnant populations
remain in a few streams in the Truckee, Carson, and Walker basins
out of an estimated 1,641.5 kilometers (1,020 miles) of historic
habitat (Gerstung 1986). Although mechanisms of stream colonization
outside of the Lahontan basin by this subspecies are uncertain,
transport by humans is suspected. Subsequently, resident stream
populations were used to stock Oregon streams during the 1970s and
1980s.

Description and Life History

Although coloration is variable, this species is generally heavily
marked with large, rounded black spots, more or less evenly distributed
over the sides, head, and abdomen. Spawning fish generally develop
bright red coloration on the underside of the mandible and on
the opercle. In spawning males, coloration is generally more intense
than in females.

Lahontan cutthroat trout are obligate but opportunistic stream
spawners. Typically, they spawn from April through July, depending
on water temperature and flow characteristics. Autumn spawning
runs have been reported from some populations. The fish may reproduce
more than once, though post-spawning mortality is high (60 to 90
percent). Lake residents migrate into streams to spawn, typically
in riffles on well washed gravels. The behavior of this subspecies
is typical of stream spawning trout; adults court, pair, and deposit
and fertilize eggs in a redd dug by the female.
Although the Lahontan cutthroat in Oregon were originally classified
as Willow-Whitehorse cutthroat trout, genetic and taxonomic investigations
led to the re-classification in 1991 (Williams 1991).

Habitat

The Lahontan cutthroat trout is one subspecies of the wide-ranging
cutthroat trout species (O. clarki) that includes at least 14
recognized forms in the western United States. Cutthroat trout
have the most extensive range of any inland trout species of western
North America, and occur in anadromous, non-anadromous, fluvial,
and lacustrine populations (Behnke 1979). Many of the basins in
which cutthroat trout occur contain remnants of much more extensive
bodies of water which were present during the wetter period of
the late Pleistocene epoch (Smith 1978).

These fish are unusually tolerant of both high temperatures (>27
C) and large daily fluctuations (up to 20 C). They are also quite
tolerant of high alkalinity (>3000 mg/l) and dissolved solids
(>10000 mg/l). They are apparently intolerant of competition
or predation by non-native salmonids, and rarely coexist with
them (Behnke 1992, LaRivers 1962).

Reasons for Decline

The severe decline in range and numbers of Lahontan cutthroat
is attributed to a number of factors including hybridization and
competition with introduced trout species, loss of spawning habitat
due to pollution from logging, mining, and urbanization, blockage
of streams due to dams, channelization, de-watering due to irrigation
and urban demands, and watershed degradation due to overgrazing
of domestic livestock (Gerstung 1986, Coffin 1988, Wydoski 1978).
Declining Lahontan cutthroat populations in the Whitehorse and
Trout Creek Mountains are a result of decades of season-long intensive
livestock grazing, recreational over-fishing, and more recently
drought conditions from 1985 to 1994.

Conservation Measures

Oregon Department of Fish and Wildlife (ODFW) surveys indicated
that Lahontan cutthroat trout populations were reduced from 1985
to 1989 by: 62 percent on Willow Creek; 69 percent on Whitehorse
Creek; 93 percent on Little Whitehorse Creek; and 42 percent on
Doolittle Creek. No Lahontan cutthroat trout were found in either
the 1985 or 1989 ODFW surveys on Fifteen Mile creek (USDI 1997).
These declining numbers prompted ODFW to close area streams to fishing
(by special order) in 1989. This closure remains in effect. Fish surveys
of area streams were conducted again in October of 1994. Although methods
vary among the conducted surveys (1985, 1989, and 1994), fish numbers
have increased in general from approximately 8,000 fish in the mid-1980s
to approximately 40,000 fish in 1994. However, in many areas,
stream conditions remain less than favorable for the cutthroat.

References and Links

Behnke, R.J. 1979. Monograph of the native trouts of the genus
Salmo of eastern North America. Unpub. Man. 215pp.